This invention relates to a system and method of estimating body states of a vehicle.
Dynamic control systems have been recently introduced in automotive vehicles for measuring the body states of the vehicle and controlling the dynamics of the vehicle based on the measured body states. For example, certain dynamic stability control systems known broadly as control systems compare the desired direction of the vehicle based on the steering wheel angle, the direction of travel and other inputs, and control the yaw of the vehicle by controlling the braking effort at the various wheels of the vehicle. By regulating the amount of braking torque applied to each wheel, the desired direction of travel may be maintained. Commercial examples of such systems are known as dynamic stability program (DSP) or electronic stability program (ESP) systems.
Other systems measure vehicle characteristics to prevent vehicle rollover and for tilt control (or body roll). Tilt control maintains the vehicle body on a plane or nearly on a plane parallel to the road surface, and rollover control maintains the vehicle wheels on the road surface. Certain systems use a combination of yaw control and tilt control to maintain the vehicle body horizontal while turning. Commercial examples of these systems are known as active rollover prevention (ARP) and rollover stability control (RSC) systems.
Typically, such control systems referred here collectively as dynamic stability control systems use dedicated sensors that measure the yaw or roll of the vehicle. However, yaw rate and roll rate sensors are costly. Therefore, it would be desirable to use a general sensor to measure any body state of the vehicles, that is, a sensor that is not necessarily dedicated to measuring the roll or yaw of the vehicle.